layout: fix issue when layout are not relayout themself after an add to parent.

kivy/uix/anchorlayout.py

@@ -14,7 +14,6 @@ To draw a button in the lower-right corner ::
 
 __all__ = ('AnchorLayout', )
 
-from kivy.clock import Clock
 from kivy.uix.layout import Layout
 from kivy.properties import NumericProperty, OptionProperty
 
@@ -49,6 +48,7 @@ class AnchorLayout(Layout):
     def __init__(self, **kwargs):
         super(AnchorLayout, self).__init__(**kwargs)
         self.bind(
+            parent = self._trigger_layout,
             padding = self._trigger_layout,
             anchor_x = self._trigger_layout,
             anchor_y = self._trigger_layout,

kivy/uix/boxlayout.py

@@ -76,6 +76,7 @@ class BoxLayout(Layout):
             padding = self._trigger_layout,
             children = self._trigger_layout,
             orientation = self._trigger_layout,
+            parent = self._trigger_layout,
             size = self._trigger_layout,
             pos = self._trigger_layout)
 

kivy/uix/gridlayout.py

@@ -213,7 +213,6 @@ class GridLayout(Layout):
 
     def __init__(self, **kwargs):
         self._cols = self._rows = None
-        self._trigger_layout = Clock.create_trigger(self.do_layout, -1)
         super(GridLayout, self).__init__(**kwargs)
 
         self.bind(
@@ -223,6 +222,7 @@ class GridLayout(Layout):
             row_force_default = self._trigger_layout,
             cols = self._trigger_layout,
             rows = self._trigger_layout,
+            parent = self._trigger_layout,
             spacing = self._trigger_layout,
             padding = self._trigger_layout,
             children = self._trigger_layout,